Scaling, corrosion, precipitates, and material defects are some problems faced by the oil and gas industry when managing production well and pipeline assets. These problems lead to diminished production in wells, casing integrity failure, and pipeline integrity failure any of which may result in costly and complex remediation measures. As such, electromagnetic techniques are commonly used to monitor the condition of the production and intermediate casing strings, tubings, collars, filters, packers, and perforations. These techniques can measure permeability data to obtain accurate measurements of tubing thickness and tubing corrosion.
This form of corrosion monitoring can be especially useful to prevent pipe integrity failures in mature wells or non-producing wells. For example, corrosion damage typically decreases the thickness of casing strings. One electromagnetic technique used for defect detection is the eddy current technique. In this technique, when a transmitter coil emits a primary electromagnetic field, or signal, eddy currents are produced in, e.g., the casing. These eddy currents then produce secondary fields, or signals, which are received by a receiver coil. When recorded and processed, this data can be employed to perform an evaluation of the casing.
However, most electromagnetic techniques and algorithms were developed for single tubing and concentric pipe configurations. Here pipe is used to denote a tubing or casing. Specifically, a configuration including a single production tubing surrounded by concentric casing is the configuration for which most techniques and algorithms such as inversion were developed. In such scenarios, it is not difficult to determine whether the location of a defect is on the production tubing or surrounding casing. However, a configuration of one or more non-concentric, or non-nested, tubings within a casing causes difficulty in pinpointing the location of defects.
It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims.